The present invention relates in general to heat exchangers, and more particularly, to a multi-chamber heat exchanger header that offers structural integrity while reducing manufacturing costs and complexity.
Headers used in multi-row mini- or micro-channel heat exchangers impart multiple manufacturing challenges. Heat exchanger headers must be strong enough to withstand the elevated pressures exerted by fluids flowing through the headers during operation. In some configurations, adjacent headers must also be in fluid communication with one another. Typically, heat exchanger headers are formed singly (e.g., one header for each row of tubes or channels) and are made from roll-formed, welded tubing or are formed by extrusion.
When multi-panel (e.g., multiple panels or slabs of adjacent micro-channels) heat exchangers are used, multiple single headers are connected together. Multiple headers are welded or brazed together at the inlet and outlet of each heat exchanger panel. In configurations where a header needs to be in fluid communication with an adjacent header, holes are first drilled into each header. The headers are then lined up so the holes in each communicate with one another and then the headers are welded or brazed together.
This process presents notable shortcomings. First, hole drilling must be performed on multiple headers in order for the headers to be in fluid communication. Second, the external welding or brazing joints between adjacent headers offer potential for leakage. Third, the headers have a thickness that is twice what is required in the area where they are connected. Because a header is formed singly and all walls of the header must be able to withstand the operating pressures of the working fluid, the header generally has a uniform thickness to ensure that the entire header is structurally sound. In the area where two headers connect (i.e. the area where the holes are drilled), the walls are prohibitively thick because each of the two headers contributes a generally uniform wall thickness.